This invention relates to a top roller which is simple in construction and has a small number of parts. A conventional top roller comprises an arbor, at both ends of which are formed rotary parts of small diameter and rotary cells rotatably mounted thereto through a bearing. The bearing comprises a needle held by a retainer. The bearing is held by a support ring, one end of which is in contact with the stepped side face of the holding portion, and the other end of which is in contact with the retainer, and by a collar ring whose displacement is regulated by a retaining ring. The support ring is elongated for detachably supporting the rotary cell and has a notch where it is in contact with the retainer. This notched part is elastic so that it will not contact the rotary part of the arbor. The end of the support ring fits a recess of the rotary cell to hold the rotary cell. When the rotary cell is drawn in its axial direction, the end of the support ring leaves the recess.
However, in conventional top rollers of this type, the distance between the centers of the two rotary cells was kept equal to the length of the spindle gauge of a spinning machine. Thus, by elongating the support ring, the centers of the bearings and of the rotary cells tended not to correspond. Further, due to the eccentric weighting of the bearings, the rotation of the rotary cells tended to be unstable, causing eccentric abrasion on the retainer or the bearing. When oil such as grease was supplied around the needle, the grease leaked out between the support rings and the arbor. Thus, it was necessary to form oil supply grooves in the rotary parts of the arbor.